High powered rifle breech

ABSTRACT

A rifle breech having a recess arranged to receive a cartridge container, the cartridge container being a tubular member the outer walls of which are engaged by the walls of the recess when inserted therein, a cartridge container having a central bore of diameter to engage and retain the rim and body of a cartridge, the cartridge container being effective in preventing rupture of the cartridge case and preventing blow back from the barrel, thereby enabling increased quantities of propellant to be used to effect consequential increased projectile velocities.

atent [1 1 [111 3,858,342 Langstord 1451 Jan. 7, 1975 [5 HIGH POWERED RIFLE BREECH 2,359,517 10/1944 Gebeau 42/15 76 I t:At W'll' L id 6 l 1 men or 222; g g g fi f gg Primary Examiner-Ben amin A. Borchelt Australia Assistant Examiner-C. T. Jordan Attorney, Agent, or Firm'.lay L. Chaskin, Esq. [22] Filed: Jan. 18, 1973 [21] Appl. No.: 324,888 ABSTRACT A rifle breech having a recess arranged to receive a cartridge container, the cartridge container being a tubular member the Outer walls of which are g g [58] w R 69 A by the walls of the recess when inserted therein, a car- 42/69 1 tridge container having a central bore of diameter to engage and retain the rim and body of a cartridge, the 'dge container being effective in preventing rup- [56] References Cited cam] ture of the cartridge case and preventing blow back UNITED STATES PATENTS from the barrel, thereby enabling increased quantities 732,540 6/1903 Garrison 42/77 of propellant {Q be used to effect consequential increased projectile velocities.

2,196,136 4/1940 Wood 102/41 7 Claims, 6 Drawing Figures H Q G 1 3 LY J/ /I HIGH POWERED RIFLE BREECH This invention relates to a rifle breech which contains an extractable cartridge container containing a cartridge and being urged by the breech bolt into engagement with an end face of a mating recess when the cartridge container is inserted, together with its cartridge, into the breech end of a rifle barrel. The invention makes possible much higher velocities than could otherwise be obtained, since the container protects the cartridge case against rupture and the cartridge obturates upon firing, not only into the container, but also into the barrel into which it projects, and thereby limits gas pressure loss.

CROSS REFERENCES TO RELATED ART Australian Pat. No. 216,678 issued to George Sullivan and entitled Lightweight firearm constitutes the closest prior art known to the applicant, said Patent disclosing a liner sleeve designated C in FIG. 9 which has the function of supporting the cartridge case against rupture, but this liner is not an extractable liner to be removed from a recess in the breech end of the barrel.

BACKGROUND OF THE INVENTION Heretofore muzzle velocities exceeding 2,500 feet per second have been achieved only occasionally with rimflre ammunition, but higher muzzle velocities are deemed to be particularly desirable in high powered rifles since they are one of the pre-requisites for increased range and flatter trajectory. The limiting factors which prevent higher velocities being achieved are:

a. the rupture of the cartridge case under the extreme pressures imposed, and j b. the loss of gas through the space which surrounds the cartridge case. This loss of gas can in some instances cause discomfort to the shooter. I- have found that it is possible to achieve pressures from 40,000 to 50,000 p.s.i., and the gas loss through the space surrounding a cartridge becomes very considerable at such high pressures.

The main object of this invention is to provide improvements whereby cartridge rupture can be substantially avoided and gas loss past the cartridge can be substantially reduced, and consequently a considerable increase in muzzle velocity of a projectile can be achieved.

BRIEF SUMMARY OF THE INVENTION Briefly the invention includes a rifle wherein the rear or breech end of the barrel contains a recess, there being a cartridge container positionable in the recess and having its outer walls engaged by the walls of the recess but being extractable from the recess, the cartridge container being retained in abutment with the end wall of the recess by the bolt when the bolt is in its locked position, so that the gas escape path can be substantially reduced, and at the same time the cartridge can be fully supported against rupture under the extreme pressures which are developed for high velocity.

It has been found through practical experimentation that a projectile having a calibre of 0.172 inch (17 calibre) and 20 grains in weight can achieve a velocity in excess of 3,300 feet per second, this representing a considerable increase on the highest velocity which has yet been achieved by prior art methods for rimfire ammunition.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention is described hereunder in some detail with reference to and is illustrated in accompanying drawings in which:

FIG. 1 is a fragmentary section through the breech end of the barrel and the barrel end of the receiver of a rifle, and showing a cartridge container entering a recess in the rear end of the barrel,

FIG. 2 is a corresponding view showing the cartridge container urged into abutment with the end face 'of the recess by the breech bolt being closed,

FIG. 3 is an enlarged section illustrating the cartridge container,

FIG. 4 is a still further enlarged section through portion of the rim of a cartridge before firing,

FIG. 5 is a view similar to FIG. 4 and illustrating the way in which the cartridge casing obturates into the container, and

FIG. 6 is a sectional view which corresponds to FIG. 3 but illustrates a second embodiment wherein the container is provided with a primer.

The breech which is illustrated herein is that of a British Lee Enfield rifle of 0.303 inches calibre, reworked for a high velocity 0.172 inch calibre projectile, but it will be clear to those skilled in the art that the invention is applicable to the breeches of many other types of rifles already in existence as 'well as other calibres.

Referring first to FIGS. 1 and 2, a rifle comprises a barrel 10, a receiver 11, a breech bolt 12 which is slidable in the receiver 11 from an open (loading) position as illustrated in FIG. 1 to a closed (locked) position as illustrated in FIG. 2. The general construction of the barrel receiver and breech bolt do not vary from prior art. However the receiver 11 is provided with a circular section recess 14 which is coaxial with the bore 15 of the barrel 10, the circular section recess 14 being arranged to contain a cartridge container 16.

The cartridge container 16 has an outer diameter such that it readily slides within the recess 14, but is accurately retained therein by the walls of the recess 14. The need for extreme accuracy of diameter does not exist, but on the other hand a greater accuracy than normally exists between a cartridge and a receiver recess is desired, and it is necessary to provide an accuracy between the end faces of about i 0.001 inches. Thus in the embodiment described, the cartridge container 16 is provided with a clearance within the limits of a standard running fit within the recess 14, that is, having a clearance of between 0.001 inch and 0.003 inch. This ensures a correct and accurate alignment of the end face 18 of the cartridge container 16 and the end face 19 of the circular section recess 14. It also ensures that the quantity of gas which can escape between the cartridge container and the recess is relatively small.

The breech bolt 12 carries on it an extractor claw designated 22, and the cartridge container 16 is surrounded near its rear end by an extractor recess designated 23 which, as shown in FIG. 2, is engaged by the claw 22 when the bolt is in its forward or locked position. The claw 22 has not been illustrated in FIG. 3 or FIG. 6.

The cartridge container 16 contains a central coaxial cylindrical bore 25 which is slightly tapered at 26 at its rear end forming an annular space 26a between the container 16 and the outer wall of a cartridge 27 adjacent the rim. The taper facilitates loading of the cartridge 27, the coaxial bore being of such diameter that it substantially sealably engages the cartridge 27. One of the difficulties encountered when firing a thin-walled rimfire cartridge is the tendency for the rear end of the cartridge to split or shear. FIGS. 4 and show how the taper 26 and space 26a will allow the cartridge to obturate in such a way that the danger of shearing is substantially reduced.

The breech bolt 12 is provided with a pin carrier 28 engaged therein, the pin carrier 28 having an aperture which slidably guides a firing pin 29, the firing pin being operated by a hammer 30 through an impact pin 31. FIG. 1 illustrates the hammer 30 in its retracted position before firing and FIG. 2 in its forward position after firing. In the embodiment shown in FIGS. 1, 2, 3, 4 and 5 the firing pin 29 is off-centre for a rimfire type of cartridge.

FIG. 3 illustrates with darkened lines the interfaces 18 and 19 of the container and recess, the interfaces between the front end of the pin carrier 28 and the rear end of the cartridge container 16, and the interfaces between the shoulder of the breech bolt 12 and the impact pin 31, all of which lie in face-to-face contact and form sealing means to limit escape of gas.

With a prototype model produced in accordance with the embodiments of FIGS. 1 through to 5, the rifle bore 15 was machined to 0.168 inch and the outer (groove) diameter to 0.172 inch. A cartridge 17 was loaded with 6.7 grains of propellant sold by Israeli Military Industries as [MI 656. This is a standard spherical type ball propellant. A 20 grains 17 calibre projectile of 0.172 inch diameter was loaded in the front end of the cartridge 26. When the cartridge was fired, the muzzle velocity of the projectile was measured at 3,31 1 feet per second, this constituting a very substantial increase over previous velocities which have been achieved with rimfire cartridges. The walls of the cartridge container 16 prevented cartridge rupture, and the conical front end 32 of the cartridge, and its forward extension 33, both obturated against the walls of the barrel. This obturation was due to the inability of the gas to otherwise escape rearwardly between the tight fitting of the cartridge of the taper 26 and the cartridge container 16, or between the cartridge container 16 and the walls of the circular section recess 14. It was noticeable that there was insufficient gas loss in a rearward direction to impart any discomfort to the shooter.

In the second embodiment of FIG. 6, the pin carrier 28 of the cartridge container 16 is constituted by a container closure member threadably engaging its rear end, the container closure member 28 containing a coaxial firing pin 39 which is arranged to be driven forwardly by a primer 40, which is in turn operated by the rifle hammer (not shown in this embodiment). The coaxial bore of the cartridge container 16 is tapered for most of its length to facilitate removal of a spent cartridge, and has an enlarged end or a step for containing the rim of the cartridge 27.

The firing pin 39 is provided with a shoulder 41 which abuts a complementary face on the front end of the pin carrier 28, while the front end of the firing pin 39 has a short coaxial circular projection 42 which is arranged to engage most but not all of the rear end of the cartridge 27, and forward impact of the firing pin 39 crushes the entire periphery of the rim of the cartridge 27 against the rim recess of the cartridge container l6, effecting very rapid ignition of the ball propellant in the cartridge. The darkened lines at the interfaces 18, 19 and 41, indicate close-fitting face-to-face conditions which limit gas loss.

A consideration of the above embodiments will indicate that the cartridge container can be utilised either as a re-usable member or it can be discarded with an empty cartridge. The existence of the tapered coaxial bore 25 in FIG. 6 assists in the sealing around the cartridge 27 at its front end.

It would be obvious to one skilled in the art that modifications to the embodiments disclosed herein can be made without departing from the invention and the scope of the invention therefore is to be determined by the recited claims.

What I claim is:

1. A rifle breech comprising a receiver, means for securing a barrel to extend forwardly of the receiver, a breech bolt slidable in the receiver from an open (loading) position to a closed (locked) position, a circular section recess in the receiver coaxial with the bore of the barrel but of larger diameter than said bore, an end face at the front end of the recess, and a cartridge container positionable in the recess and having its outer walls engaged by the walls of the recess but being extractable from the recess, the breech bolt urging the front end of the cartridge container into abutment with the recess end face when the bolt is in locked position, the cartridge container having a central bore extending the length of the container, the central bore having a diameter to retain a cartridge therein, the central bore having adjacent a rear end an internal taper which diverges rearwardly and terminates in a diameter greater than the diameter of and spaced from the walls of a cartridge to be contained in said central bore but less than the rim diameter of said cartridge, wherein between the central bore taper and cartridge wall there is formed an annular space adjacent to the cartridge rim.

2. A rifle breech according to claim 1 wherein said cartridge container has an outer diameter of between 0.001 inch and 0.003 inch less than the diameter of said circular section recess.

3. A rifle breech according to claim 1 further comprising a cartridge containing opening in the rear end of the bore of the barrel but positioned forwardly of said circular section recess, of complementary shape to the shape of the front end of the cartridge and arranged to engage the front end walls of said cartridge when it is contained in the cartridge container and the cartridge container is contained in said circular section recess.

4. A rifle breech according to claim 1 further comprising a pin carrier on the front end of said bolt, an aperture in the pin carrier, and a firing pin retained in the aperture and slidably movable therein.

5. A rifle breech according to claim 1 further comprising an extractor recess surrounding the cartridge container near its rear end.

6. A rifle breech according to claim 1 further comprising a closure member threadably engaging the container and closing the rear end of said coaxial bore, an aperture extending coaxially through the closure member, and a firing pin axially movable in the aperture,

circular projection which engages most but not all of the rear end of a cartridge when in the carrier, and crushes the entire periphery of the rim upon forward movement of the firing pin. 

1. A rifle breech comprising a receiver, means for securing a barrel to extend forwardly of the receiver, a breech bolt slidable in the receiver from an open (loading) position to a closed (locked) position, a circular section recess in the receiver coaxial with the bore of the barrel but of larger diameter than said bore, an end face at the front end of the recess, and a cartridge container positionable in the recess and having its outer walls engaged by the walls of the recess but being extractable from the recess, the breech bolt urging the front end of the cartridge container into abutment with the recess end face when the bolt is in locked position, the cartridge container having a central bore extending the length of the container, the central bore having a diameter to retain a cartridge therein, the central bore having adjacent a rear end an internal taper which diverges rearwardly and terminates in a diameter greater than the diameter of and spaced from the walls of a cartridge to be contained in said central bore but less than the rim diameter of said cartridge, wherein between the central bore taper and cartridge wall there is formed an annular space adjacent to the cartridge rim.
 2. A rifle breech according to claim 1 wherein said cartridge container has an outer diameter of between 0.001 inch and 0.003 inch less than the diameter of said circular section recess.
 3. A rifle breech according to claim 1 further comprising a cartridge containing opening in the rear end of the bore of the barrel but positioned forwardly of said circular section recess, of complementary shape to the shape of the front end of the cartridge and arranged to engage the front end walls of said cartridge when it is contained in the cartridge container and the cartridge container is contained in said circular section recess.
 4. A rifle breech according to claim 1 further comprising a pin carrier on the front end of said bolt, an aperture in the pin carrier, and a firing pin retained in the aperture and slidably movable therein.
 5. A rifle breech according to claim 1 further comprising an extractor recess surrounding the cartridge container near its rear end.
 6. A rifle breech according to claim 1 further comprising a closure member threadably engaging the container and closing the rear end of said coaxial bore, an aperture extending coaxially through the closure member, and a firing pin axially movable in the aperture, and a primer on the rear end of said pin, so arranged that ignition of the primer drives said firing pin forwardly.
 7. A rifle breech according to claim 6 wherein the front end of said firing pin comprises a short coaxial circular projection which engages most but not all of the rear end of a cartridge when in the carrier, and crushes the entire periphery of the rim upon forward movement of the firing pin. 